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Our Energy Future in 900 words

Sun, 2009-02-15 01:45 — Brian McGavin

This was originally published on 15 January 2009

World energy consumption grew by 11 per cent between 1989 and 1999. Most forecasts project energy demand will grow a further 60 per cent between 2002 and 2030, due to rising global population and economic growth in countries like China and India. (source: chief executive BP oil). Yet, almost all petroleum geologists agree that oil production will peak within 20 years, by which time half of the Ultimate Recoverable Resource will have been consumed. Natural gas will peak shortly after oil. After this, consumption has to fall, eventually to zero. Were consumption to stay constant, proven reserves of oil would be largely depleted within 40 years and natural gas not long after.

Coal consumption

Coal consumption is now growing at twice the average of all fuels, with China accounting for 80 per cent of the growth. If consumption continues at the present rate, proven recoverable reserves will last between 100 and 155 years. With coal, a substantial part of the problem is how much energy it takes to extract it. (source: AF Optimum Population Trust (OPT).

All fossil-fuels peak estimation

However, Professor David Rutledge of the California Institute of Technology recently made a compelling case for the peak of all fossil fuel energy production occurring in 2021 and for 90% of all the fossil fuels that we will ever extract being consumed by 2076. (October 2007: Hubbert’s Peak, the Coal Question and Climate Change).

While the 1990s saw the largest discovery of oil in 20 years in the Gulf of Mexico, this estimated new reserve of 700 million barrels would meet America’s then daily consumption of 17m barrels for just 42 days! (source: Albert Bartlett, Univ. of Colorado). By 2005, US oil consumption had increased by over a quarter, to 21million barrels a day, according to the US Energy Information Agency.

Efficiency

Average efficiency of coal fired power stations is about 35 per cent, but efficiencies could possibly be increased to nearer 46 per cent. However, limiting their carbon pollution by pumping effluent gasses into old oil or coal fields is energy intensive and expensive and there is no efficiency saving by adding carbon capture technology to power plants. As a result no commercial system has been built (source: the Economist magazine, 2 December 2006).

Renewables

Renewables like wind, wave, tidal and photovoltaics are all uncontrollable power sources that together, are limited to supplying at most about 20 per cent of total electricity supply due to the uncontrollable nature of wind, solar and wave supply. Their variable power output causes efficiency problems for traditional power plants that will still be needed to provide on-line back up power. However, Photovoltaic and Solar Thermal Energy has produced negligible results so far - about 1/700th of all commercial energy.

While world renewable energy supply grew by an average 2.3 per cent a year from 1971 to 2004, according to the International Energy Agency in Feb 2006, world population growth continued to increase the number of energy consumers, by 1.6 per cent a year. (source: OPT energy web pages)

Ethanol

Ethanol, produced either from corn or sugarcane, has a low output power density, containing 33 per cent less energy than the same amount of petrol. Eighteen per cent of U.S. corn goes to producing ethanol, but it provides only 1 per cent of the liquid fuel used in the U.S. (Pimentel et al). Similarly, biodiesel contains 12 per cent less chemical energy than diesel oil.

Expanding ethanol fuel production uses vital land needed for food production for ever-increasing populations and risks further widespread forest clearance to grow crops for fuel. Creating ethanol from cellulose waste is seen as a hopeful way forward, but no one has yet demonstrated a method by which more energy could be extracted than the energy required as inputs. The ‘Energy hopefuls’ talk about scientists finding better enzymes, but so far, this is just speculation.

'Net energy capture'

The ‘net energy capture’ would be a revealing figure if its value could be agreed, says OPT’s Andrew Ferguson, but we need to know how much of the by-product can be counted as an output and how much of the total crop can be utilised without causing soil degradation. In the case of corn, total yield is about 15,000 kg/ha (dry), with about half of this being grain and the rest being leftover stubble. (Pimentel and Pimentel,1996). Growing corn is prone to cause soil erosion and sugarcane causes even greater erosion. All the remaining stubble should be returned to the ground to return nutrients. The ‘energy balance’ of producing ethanol from corn can therefore be assessed as positive or negative, depending on judgement. A zero energy balance means that producing ethanol from biomass is not an energy transformation that produces useful energy; but merely a way of using other forms of available energy to produce energy in a liquid form.

Hydrogen a carrier, not a fuel

Hydrogen fuel cells are promoted as a clean fuel and only emit heat and water as waste. However, hydrogen is an energy-carrier, like electricity, not an energy source and needs electric power to extract hydrogen from water through electrolysis. It is only as clean as the fuel source used to produce it and provides only a quarter the energy as the same volume of petrol, diesel or kerosene (source: Prof. R Mann, Manchester University) – a significant problem for aircraft.

Biodiesel

Biodiesel contains 12 per cent less chemical energy than diesel oil and is five per cent less fuel efficient when burnt in an engine. A litre of ethanol contains 33 per cent less energy than a litre of petrol. In addition, ethanol blended fuels cannot easily be transported by pipeline as the ethanol attracts water, making it ineffective as a fuel. It must be transported by road, causing further fuel inputs. (Ecologist Magazine March 2007).

Electricity

In 2004, 50% of the electricity produced in the United States came from coal, 20% from nuclear, 18% from natural gas, 7% from hydro-electricity, 3% from petroleum and the remaining 3% from geothermal, biomass and solar.

A typical sized power station generates around 1000 megawatts (MW), where one MW equals a million watts. In 2002 average power demand in the UK was around 45 gigawatts (GW) or 45 billion watts. With average demand about 66% of peak demand, peak UK demand was then about 68 GW.

Geothermal

Geothermal energy[1] can be extracted without burning fossil fuel and produces only a sixth of the carbon dioxide of a natural gas-fuelled power plant, but heat pumps are expensive to install in houses. While it is very successful in a country like Iceland, where the capital is heated by geothermal energy, it is not as successful in the many places where there is no abundant heat sink in the soil.

Nuclear

Some say nuclear power is the only realistic answer to growing energy needs, despite the huge problems of storing deadly waste and potential terrorist threats. A 1,000-megawatt nuclear power station produces around 30 metric tonnes of high-level waste a year, which remains hazardous to life for thousands of years.

Nuclear fission generates just 2.5 per cent of the world’s electricity[2] and in most industrial countries nuclear supplies about 20 per cent of energy needs. In an extensive investigation, the June 2006 Ecologist magazine noted that Australia has 40 per cent of the world’s estimated 3.5 million tonnes supply of uranium. The industry estimates this would only fuel current nuclear capacity for another 45-50 years, but the potential doubling in number of fission reactors across the world could see commercially extractable uranium fuel ore run out in 20 years. As shortages loom, it is unlikely that nuclear nations with uranium ore, such as Russia, Canada and the USA, will be likely to sell it. The spot market price has risen 600 per cent between 2002 and 2006. The UK and other nuclear power generating countries will be increasingly reliant on remaining supplies from Kazakhstan, South Africa and Brazil and if major expansion takes place, will be investing billions to produce long-term deadly waste for only a short-term energy gain.

Nuclear reactors need 30 million gallons of water daily as coolant to prevent potential meltdown. With sea levels predicted to rise by half a metre by the end of this century, according to the International Panel on Climate Change, all the UK’s nuclear reactor sites are at potential risk of flooding and erosion. Major new reactor construction programmes will add millions of tonnes to CO2 emissions, though nuclear generated power will help to reduce carbon emissions. If the UK opts to keep nuclear power supplying around 20 per cent of energy needs it is likely 10 new reactors will need to be built. Worldwide, around 80 new reactors are envisaged. However, many countries are considering increasing their nuclear capacity further.

A 1998 study for the Canadian nuclear industry found that for every unit of useable high-grade (one per cent) uranium ore recovered, 20 times that amount of CO2 is released into the atmosphere. Most uranium deposits are only found in concentrations of 0.02 or less, making the true picture more problematic. Attempts to extract uranium from seawater would take three times as much energy as would eventually be produced in power output and involves highly polluting chemicals.

One hope is that reactors that breed their own fuel will come on stream. There are only three fast-breeder reactors in the world, in Russia, Japan and France, but only the Russian reactor is still operating and none has successfully managed to breed fuel. According to environmental consultancy Ceedata, if the technology could be made to work, the plutonium fuel to start up two reactors could theoretically double in size every 40 years - enough fuel to power up two more reactors. Optimistic forecasts say the technology might be ready in 20 years.

Energy fantasies?

Contrary energy messages include claims by Solar Century, a company promoting solar power, that if every south facing roof in Britain carried a solar panel, this would generate 85% of UK electricity needs. The same Guardian article of March 7, 2000 also quotes Shell Oil claims that if alternative ‘green’ energy sources were developed these technologies could provide up to 50% of the world’s energy needs by 2050.

Friends of the Earth

Friends of the Earth in its “Tomorrow’s World in Ten Minutes” overview of environmental challenges claims we have the technology to cut home energy use by 95 per cent, increase waste recycling by 80 per cent and vehicle fuel efficiency by 10 times. It says we could produce the food we need with a “tiny fraction” of the chemicals and fossil energy now used. It assumes a stable world population in 2050 without saying how all this can be achieved.

However, most of these claims are totally unrealistic, says OPT’s Andrew Ferguson, because they ignore the problem of intermittency of renewable energy sources, like wind turbines and low power density in biomass and hydro, So there are no grounds for confidence in the belief of a transition to a renewable energy world.

[1] Traditional geothermal, not deep geothermal or hot rocks.
[2] This figure, from The Ecologist is much smaller than the figure given by the International Energy Association, which was 6.8 in 2008. (See: www.iea.org/textbase/nppdf/free/2004/keyworld2004.pdf) The IEA predicts that nuclear generation in 2010 will be 6.2% of the total energy mix and that in 2030 it will be 4.3%, with - surprisingly - greater use of petroleum. I welcome readers' comments on these figures.

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